1. Field of the Invention
This invention relates to chemical apparatus for the automatic analysis of biological fluids, and more particularly, to an incubator for use in such apparatus.
2. State of the Prior Art
In recent years, a number of automated systems have been developed for carrying out quantitative chemical analyses of fluid samples. Most of the commercially-available systems utilize liquid reagents and require analyzer equipment having intricate solution handling and transport capabilities. One widely used system, shown in U.S. Pat. No. 2,797,149, employs a continuous-flow technique in which successive samples are separated from one another by immiscible fluid segments such as gas or air bubbles. Such a system is complex and expensive, requires skilled operators, and necessitates cleaning operations.
In clinical analyzers for measuring a characteristic of a substrate in liquid form, incubators are employed to bring the substrate to a desired state for analysis. These incubators generally comprise: a plurality of stations for the substrates, often mounted for rotation about an axis; a temperature control system including a heater; and a radiometer of some type, such as a reflectometer, designed to selectively scan each of the stations. A relatively simple example of such an incubator is shown in U.S. Pat. No. 3,616,264, whereas U.S. Pat. Nos. 3,756,920; 3,758,274; 3,788,816 and 3,790,346 illustrate more complex apparatus. In this art, however, no provision is made for an incubator in which substrates can be readily moved in and out of a conveyor contained within the incubator.
As an alternative to liquid analysis systems, various essentially-dry analytical elements have been adopted for automated test procedures. Although these elements offer substantial storage, handling and other conveniences, as compared to "wet-chemistry," they have enjoyed only limited success and have been used primarily for qualitative and semiquantitative test purposes. Apparatus for use with analytical elements in the form of continuous webs is shown in U.S. Pat. Nos. 3,036,893, and 3,526,480. In this apparatus, the web is passed through a relatively simple incubation station; however, since the reagents are contained on the web in a predetermined sequence, the versatility of this apparatus is quite limited.
The Binnings et al., U.S. Pat. No. 3,574,064, discloses apparatus in which glass slides are fed from a single supply station onto a turntable. Slides carried on the turntable are moved past a metering station, and then through wash and incubation stations spaced around the periphery of the turntable. Slides processed by the apparatus are ejected from the turntable into a slide receiver adjacent the slide supply station. There is no provision for automatic analysis of the processed slides, and they must be manually removed from the slide receiver for examination under a laboratory microscope.
U.S. Pat. No. 3,770,382, to Carter et al. discloses a clinical analyzer in which test packs containing a sample fluid and reagents are carried on a continuous chain which moves the packs through a plurality of stations in a heat-controlled chamber. Mounted within the chamber, at the entrance thereof, is a preheater which is adapted to raise the test packs to a desired temperature range. Since the Carter et al. heat-controlled chamber is large enough to include most of the analyzer components, including the analysis means, considerable heating equipment is required to maintain a precise temperature control.
The Wall, U.S. Pat. No. 2,055,021, discloses an intermittent drive mechanism comprising a worm in which a first thread portion has a zero helix angle and a second thread portion is disposed at an angle to the first thread portion. There is no suggestion in this patent of the use of such a drive mechanism in a chemical analyzer.